This invention relates to coating compositions curable by exposure to high-energy radiation.
It is known that high-energy radiation can be used to effect curing of polymerizable liquid polymers, monomers and solutions and dispersions of polymers in monomers. It is also known that high-energy radiation has a number of distinct advantages over conventional methods of effecting polymerization and cross-linking using catalytic agents only. High-energy radiation is especially useful for the curing of coatings on wood and wood products, fabrics, rubber, glass, metal and similar substrates. Through its use the sometimes lengthy induction period associated with catalyst-induced curing can be avoided, compositions having indefinite pot lives can be employed and, in many instances, superior coating-to-substrate bonding can be achieved.
To enable the use of high-energy radiation curing to best advantage, coating compositions are needed which are capable of being rapidly cured at reasonable dose rates, which give good single coat coverage and which do not excessively penetrate porous substrates. For application to vertical surfaces, non-drip, low-flow compositions are essential. When high-energy ionizing radiation, such as an electron beam, is to be employed in air, it is also desirable that the composition have a high viscosity which minimizes oxygen absorption and oxygen inhibition of curing at the surface of the coating.